Adjustable spanner

ABSTRACT

This specification discloses an adjustable spanner that has a handle provided with a first jaw at one end. A lever is pivotally connected to the handle and has coupled at one end a second jaw. The jaw is coupled to the lever by a link. The link is pivotally connected at one end to the second jaw and pivotally connected at another end to the lever. A cam is carried in slot formed in link. An elongate slot is cut in a head portion of the handle. As the lever is pivoted with respect to the handle the cam rides in slot and the jaws and move linearly with respect to each other. The cam and slot cooperate to form a locking mechanism. The locking mechanism has a free state corresponding to the cam being disengaged from the slot in which the jaws are able to move relative to each other and the locking state in which the cam engages the slot whereby the jaws are locked against movement away from each other. The locking mechanism remains in the free state until the lever is pivoted in a first direction relative to the handle to a position where the jaws can grip a nut or the like placed therebetween. Upon further movement in the first direction, the lever then operates via the link to rotate the cam into engagement with the slot thereby locking the jaws against movement away from each other. Upon releasing the handle, a return spring rotates the cam in an opposite direction lifting it away from slot so as to return the locking mechanism to the free state.

FIELD OF THE INVENTION

This invention relates to an adjustable spanner.

DISCUSSION OF PRIOR ART

Adjustable spanners are particularly useful because they can accommodatevarious sizes of nuts, bolts and like. The most common type ofadjustable spanner comprises a fixed jaw, and a moveable jaw which isjournaled to a worm gear adapted to be rotated by the thumb of a user.Rotation of the worm gear causes the moveable jaw to move relative tothe fixed jaw to facilitate gripping of nuts, bolts and the like ofvarious sizes between the jaws. One difficulty with this type ofadjustable spanner is that adjusting the spanner to engage a nut of aparticular size can be time-consuming, particularly in a confinedenvironment where the nut cannot be seen or where there is insufficientroom to allow the user to adjust the spanner in situ. A further inherentdifficulty is that the worm gear is designed to leave some play betweenthe jaws. This play can sometimes result in the spanner slipping underpressure.

SUMMARY OF THE INVENTION

The present invention was developed with a view to providing anadjustable spanner which can more readily and quickly be adjusted to therequired setting with minimal risk of slippage.

To this end, the present invention provides an adjustable spannercomprising:

a handle provided with a first jaw at one end;

a lever having a second jaw coupled thereto at one end, the lever beingpivotally connected to the handle and juxtaposed so that pivotalmovement of the lever relative to the handle effects movement of thefirst jaw relative to the second jaw whereby the first and second jawscan grip an article placed therebetween; and,

locking means having a free state in which the jaws are able to moverelative to each other and a locking state in which the jaws are lockedagainst movement away from each other, said locking means cooperatingwith said lever so as to remain in said free state until the lever ispivoted in a first direction relative to the handle to a position wherethe jaws grip an article placed between the first and second jaws,whereby, upon further movement in said first direction the leveroperates to change the state of the locking means to the locking state,thereby locking the jaws against movement away from each other.

Preferably, said locking means comprises first and second mutuallyengagable elements, said elements being disengaged when the lockingmeans is in the free state and being engaged when the locking means isin the locking state, said first element being associated with saidlever so that upon said further movement, said lever operates to effectengagement of said first and second elements.

Preferably, said locking means comprises a link having a first pivotconnection to said one end of the lever and a second pivot connection tosaid second jaw thereby coupling the second jaw to the lever.

Preferably said first element is carried by said link.

Preferably, said link is provided with a slot for receiving said firstelement, said slot being shaped to substantially prevent rotation ofsaid first element within said slot.

Preferably, said locking means further comprises a stop for stoppingrotation of the link about the first pivot connection in a seconddirection beyond a predetermined angular position relative to the lever,and biasing means for biasing said link to rotate in said seconddirection toward said predetermined angular position, whereby, upon saidfurther movement, said lever operates to cause rotation of the linkabout said first pivot connection in a direction opposite said seconddirection away from said predetermined angular position to move saidfirst element into engagement with said second element.

Preferably, said first and second elements comprise respective bearingsurfaces configured so as to lock together upon mutual engagement.

Preferably, each bearing surface comprises first and second surfaceportions arranged so that when said locking means is in said lockingstate the first surface portions engage each other and the secondsurface portions engage each other.

Preferably, said first element comprises cam means on which said firstand second surface portions are formed.

Preferably, said second element comprises an elongate slot cut in saidhandle extending in a direction substantially parallel to the directionof relative movement of the first and second jaws, and said first andsecond surface portions are formed on opposite longitudinal surfaces ofthe slot.

Preferably, said first surface portions are provided with mutuallyengagable teeth.

Preferably, the second surface portion of said cam means is curved.

Preferably, the second surface portion of said cam means is planar.

Preferably, said adjustable spanner further comprises a second biasmeans acting between said lever and said handle acting to bias saidlever to pivot in a direction opposite said first direction and urge thelocking means toward the free state.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention can be described by way of example only,with reference to the accompanying drawings in which:

FIG. 1 is a front view of the adjustable spanner in a fully openedposition;

FIG. 2 is a front view of the adjustable spanner in a fully closedposition;

FIG. 3 is is an exploded view of the adjustable spanner;

FIG. 4 is a front view of an upper portion of the spanner prior toengagement with a nut; and,

FIG. 5 is a front view of an upper portion of the spanner uponengagement of a nut.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in the accompanying drawings, an adjustable spanner 10comprises a handle 12 having a head portion 14 at one end, the headportion being provided with a first jaw 16. In the present embodiment,the handle 12 is made of two complimentary halves 18 and 20 havingmatching features (refer FIG. 3). A lever 22 having a second jaw 24coupled thereto at one end is pivotally connected to the handle 12 bymeans of a screw fastener 26 which threadingly engages the handle 12 andpasses through an elongate slot 28 formed in the lever 22. The handleand lever are juxtaposed so that pivotal movement of the lever 22relative to the handle 12 effects movement of the first jaw 16 relativeto the second jaw 24 whereby the first and second jaws can grip anarticle such as a nut or bolt head 30 therebetween (refer FIGS. 4 and5). The spanner 10 further includes a locking means 32 having a freestate (shown in FIGS. 1, 2 and 4) in which the jaws 16 and 24 are ableto move relative to each other, that is both away and toward each other,and a locking state, shown in FIG. 5, in which the jaws 12 and 24 arelocked against movement away from each other. The locking meanscooperates with the lever 22 so as to remain in the free state until thelever is pivoted in a first direction relative to the handle indicatedby arrow 34 to a position where nut 30 is engaged between the jaws. Uponfurther movement of the lever in direction 34, the lever operates tochange the state of the locking means to the locking state as shown inFIG. 5 thereby locking the jaws against movement away from each other.

The locking means 32 comprises a link 36 and first and second mutuallyengagable elements in the form of cam 38 and longitudinal slots 40,respectively. The link 36 has a first pivot connection 42 to the leverand a second pivot connection 44 to the second jaw 24. A slot 46 forreceiving the cam 38 is formed in the link 36 at an end distant thelever 22. A projection 48 having an arcuate bearing surface extends froma back side 50 of the link 36 adjacent each longitudinal side of slot46. The projections 48 are received in hole 52 formed in the jaw 24 toprovide the second pivot connection 44.

An end of the link 36 opposite the slot 46 is provided with a stop 54adapted to abut against a shoulder 56 formed in the lever 22 to preventclockwise rotation of the link 36 beyond a predetermined angularposition relative to the lever 22. A spring 58 is connected between thelink 36 and lever 22 to bias the link 36 to rotate in the clockwisedirection to the predetermined angular position where the stop 54 abutsthe shoulder 56.

The cam 38 has a central body 60 with identical cam sections 62extending from opposite sides. The central body 60 is of the shapecomplimentary to that of the slot 46 so as to substantially preventrotation of the cam 38 within the slot 46. Each cam section 62 includesa bearing surface 64 a first portion of which is provided with aplurality of teeth 66. A second portion 67 of bearing surface 64 iscurved.

One longitudinal slot 40 is formed in each halve 18 and 20 of the headportion 14 and extend in the direction substantially parallel to thedirection of relative movement of the jaws 16, 24. The peripheralsurface of slot 40 forms a bearing surface 68 for engagement with thecam 38. The lower longitudinal portion of bearing surface 68 is providedwith a rack of teeth 69. The upper longitudinal portion 71 of thebearing surface 68 is a planar surface.

The cam sections 62 ride in the slots 68 when the handle is pivotedabout screw fastener 26. Abutment of the cam sections 62 with ends ofthe slots distant the first jaw 14 limits the maximum distance betweenthe jaws to that shown in FIG. 1.

The second jaw 24 includes a carriage 70 provided on opposite sides withlongitudinal ribs 72 of arcuate cross-section shape. A lobe 74 throughwhich the hole 52 is formed depends from the ribs 72. Obliquelyextending grooves 76 are formed in the head portion 14 to receive theribs 72 so as to key the second jaw 24 to the handle 18 for linearmovement.

A lower portion 78 of the lever 22 is provided with an elongate flange79 extending laterally from a side distant the handle 12. The flange 79forms a bearing surface for the hand of a user when pivoting the lever72 in direction 34. The lower portion 78 is shaped on a side oppositeflange 79 for engaging one side of a hair-pin like spring 80. The spring80 includes a leg 82 which abuts the interior of a side surface 84 ofthe handle 18. The spring acts to pivot the handle in a directionopposite that indicated by arrow 34 so that the jaws 16 and 24 are inthe position shown in FIG. 1.

The lever 22 moves within a cavity formed in the handle 12 between thehalves 18,20. When the lever is pivoted in the clockwise directionrelative to the handle to a position where jaws 16 and 24 meet the lowerportion 78 is received in the cavity with flange 79 abutting the handle12 as shown in FIG. 2.

The operation of the adjustable spanner 10 will now be described.

Prior to use, the spring 80 acts to bias the lever 22 in ananticlockwise direction about the screw 26 so that the distance betweenjaws 16 and 24 is at a maximum. The spring 58 biases the link 36 to aposition where the stop 54 abuts the shoulder 56. When in this position,the bearing surface 64 of cam 38 is spaced above and disengaged from therack 40. This corresponds to the locking means 32 being in the freestate.

If the handle 22 is pivoted in clockwise direction 34 against the biasof spring 80, the second jaw is caused to slide in a linear path towardthe first jaw 16 by virtue of the engagement of the ribs 72 in thegrooves 76. The spring 58 holds the stop 54 against the shoulder 56therefore maintaining the locking mechanism 32 in the free state (referFIG. 4). Due to the inclination of grooves 76 the pivotal movement ofthe lever is accompanied by linear movement in the general direction ofthe length of the lever toward the first jaw 16. This linear movement isaccommodated by virtue of the pivot connection 44 and slot 28. Thelocking means 32 remains in the free state during this movement untilthe nut 30 is gripped between the jaws 16 and 24.

Continued pivotal movement of the lever 22 in direction 34 causes thelink 36 to rotate in an anticlockwise direction about pivot 42 againstthe bias of spring 58. Accordingly, the cam 38 is likewise rotated sothat teeth 66 engage the teeth on rack 69, and portion 67 of bearingsurface 64 abuts the upper longitudinal portion 71 of bearing surface 68as shown in FIG. 5. The locking means 32 is now in the locking state andthe jaws 16 and 24 are locked against movement away from each other. Inthis configuration the cam 38 and a particular cam sections 62 act as awedge in slot 40. Provided the lever is maintained in this positionrelative to the handle, the spanner 10 can now be used to apply torqueto the nut 30 in the desired direction for fastening or loosening. Thereaction force to the applied torque on second jaw 24 acts on pivotconnections 42 and 44 to urge the cam 38 to rotate in the anticlockwisedirection to assist in the wedging action of cam 38.

When the handle 22 is released, spring 58 initially acts to rotate thelink 36 in the clockwise direction to lift the cam 38 out of engagementwith slot 40. The locking means 32 is now in the free state and the jaws24 and 16 can move relative to each other. The spring 80 acts on thelever 22 to cause it to pivot in an anticlockwise direction therebyreturning the spanner to the configuration shown in FIG. 1.

Now that an embodiment of the invention has been described in details,it will be apparent to those skilled in the relevant arts that numerousmodifications and variations may be made without departing from thebasic inventive concepts. For example, the handle 12 can be made from asingle piece of cast and machined metal rather than separate halves 18,20. In addition, the lever 22 can be shaped so that rather thanextending through the handle 12 it is located exterior of the handle 12.This will avoid the need to form the handle with an internal cavity foraccommodating the lever and may simplify manufacture. Furthermore, thesecond portion 67 of bearing surface 64 can be planar rather than curvedto give greater area of contact with the upper longitudinal portion 71of bearing surface 68 when the locking means is in the locking state. Inthe present embodiment the centre of rotation of the cam 38, whichcorresponds with the centre of slot 46, moves in a path substantiallycoincident with the longitudinal centre line of slot 40 as the lever ispivoted with respect to the handle. However, in an alternative form thecentre of rotation of cam 38 can be offset from the longitudinal centreline of slot 40 towards the jaws 16, 24. This is most easily achieved byforming the slot 46 closer to the jaw 24. The effect of this, when thespanner is in use, is that a portion of the reaction force applied byjaw 24 creates torque on the cam 38 acting in the anticlockwisedirection to further amplify the wedging effect of cam 38 in slot 40.All such modifications and variations are deemed to be within the scopeof the present invention the nature of which is to be determined fromthe aforegoing description and the appended claims.

The claims defining the invention are as follows:
 1. An adjustablespanner comprising:a handle provided with a first jaw at one end; alever having a second jaw coupled thereto at one end, the lever beingdirectly pivotally connected to the handle and juxtaposed so thatpivotal movement of the lever relative to the handle effects movement ofthe second jaw relative to the first jaw whereby the first and secondjaws can grip an article placed therebetween; locking means having afree state in which the jaws are able to move relative to each other anda locking state in which the jaws are locked against movement away fromeach other, said locking means cooperating with said lever so as toremain in said free state until the lever is pivoted in a firstdirection relative to the handle to a position where the jaws grip anarticle placed between the first and second jaws, whereby, upon furthermovement in said first direction the lever operates to change the stateof the locking means to the locking state, thereby locking said jawsagainst movement away from each other; said locking means comprisingfirst and second mutually engagable elements and a link having a firstpivot connection to said one end of said lever and a second pivotconnection to said second jaw thereby coupling said second jaw to saidlever, said first element being carried in a slot provided in said link,the slot shaped to substantially prevent rotation of the first elementwithin the slot, and said elements being disengaged when the lockingmeans is in said free state and being engaged when the locking means isin said locking state, said first element associated with the lever sothat upon said further movement, said lever operates to effectengagement of said first and second elements.
 2. An adjustable spanneraccording to claim 1, wherein said locking means further comprises astop for stopping rotation of the link about the first pivot connectionin a second direction beyond a predetermined angular position relativeto the lever, and biasing means for biasing said link to rotate in saidsecond direction toward said predetermined angular position, whereby,upon said further movement, said lever operates to cause rotation of thelink about said first pivot connection in a direction opposite saidsecond direction away from said predetermined angular position to movesaid first element into engagement with said second element.
 3. Anadjustable spanner according to claim 2, wherein said first and secondelements comprise respective bearing surfaces configured so as to locktogether upon mutual engagement.
 4. An adjustable spanner according toclaim 3, wherein each bearing surface comprises first and second surfaceportions arranged so that when said locking means is in said lockingstate the first surface portions engage each other and the secondsurface portions engage each other.
 5. An adjustable spanner accordingto claim 4 wherein said first element comprises cam means on which saidfirst and second surface portions are formed.
 6. An adjustable spanneraccording to claim 5, wherein said second element comprises an elongateslot cut in said handle extending in a direction substantially parallelto the direction of relative movement of the first and second jaws, andsaid first and second surface portions are formed on oppositelongitudinal surfaces of the slot.
 7. An adjustable spanner according toclaim 6, wherein said first surface portions are provided with mutuallyengagable teeth.
 8. An adjustable spanner according to claim 7 whereinthe second surface portion of said cam means is curved.
 9. An adjustablespanner according to claim 7, wherein the second surface portion of saidcam means is planar.
 10. An adjustable spanner according to claim 1,wherein said second jaw is keyed to said handle for linear movementrelative to said first jaw.
 11. An adjustable spanner according to claim1, wherein said second jaw is keyed to said handle for oblique linearmovement relative to said first jaw.
 12. An adjustable spanner accordingto claim 1, further comprising a second bias means acting between saidlever and said handle acting to bias said lever to pivot in a directionopposite said first direction and urge the locking means toward the freestate.